Ice storm

I would guess that this happens on the edges of weather fronts, when it's warm enough above to rain (instead of snow) and cold enough below to freeze (instead of drain). The result? A thin, brittle coating that just about dropped me on my butt when I half-skated down the driveway to retrieve the garbage cans today. But when the wind blows hard enough to move the lighter tree branches, you also get a crackle all around you that's one of the signature sounds of winter.

Very cool if all you're doing is peeking your head outdoors to listen (or moving your car into the garage temporarily).